Various techniques for controlling and operating DC variable speed electric motors are implemented in conventional systems. Such techniques are sometimes implemented specifically in the context of automobiles, and specifically for the heating, ventilating, and air conditioning (“HVAC”) systems in automobiles to control and operate a DC motor component of the system. In many such instances, circuitry is implemented to provide a linear motor speed response with respect to a control signal.
Motor noise is generally a problem in such systems, particularly in the context of an HVAC system. Some known systems employ filter circuitry integrated with a motor to improve, i.e., reduce, motor noise. Some of the disadvantages of such techniques are that it adds to the cost of manufacture (e.g., the fewer components in the motor in the system, potentially the less costly to produce) and adds to the complexity of designing systems around the motor. More complicated systems have a tendency to require additional repair or replacement, as well.
To implement linear control for the motor in such systems, circuitry that establishes a control loop with the motor is sometimes implemented. The implementation of a control loop may often need to meet various criteria of its own that may exist irrespective of considerations for the motor. For example, the control loop may need to sufficiently vary a supply current to meet system requirements and may need to address concerns in variation and noise in battery signals.
Thus, it is desired to provide linear motor control that avoids the disadvantage of requiring filter circuitry.